Stages Of Colon Cancer

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Stage 0: The cancer is found only in the innermost lining of the colon or rectum. Carcinoma in situ is another name for Stage 0 colorectal cancer. Stage I: The tumor has grown into the inner wall of the colon or rectum. The tumor has not grown through the wall. Stage II: The tumor extends more deeply into or through the wall of the colon or rectum. It may have invaded nearby tissue, but cancer cells have not spread to the lymph nodes. Stage III: The cancer has spread to nearby lymph nodes, but not to other parts of the body. Stage IV: The cancer has spread to other parts of the body, such as the liver or lungs. Recurrence: This is cancer that has been treated and has returned after a period of time when the cancer could not be detected. The disease may return in the colon or rectum, or in another part of the body.

This answer is based on source information from National Cancer Institutef.

N categories indicate whether or not the cancer has spread to nearby lymph nodes and, if so, how many lymph nodes are involved. To get an accurate idea about lymph node involvement, most doctors recommend that at least 12 lymph nodes be removed during surgery and looked at under a microscope. Nx: No description of lymph node involvement is possible because of incomplete information. N0: No cancer in nearby lymph nodes. N1a: Cancer cells are found in 1 nearby lymph node. N1b: Cancer cells are found in 2 to 3 nearby lymph nodes. N1c: Small deposits of cancer cells are found in areas of fat near lymph nodes, but not in the lymph nodes themselves. N2a: Cancer cells are found in 4 to 6 nearby lymph nodes. N2b: Cancer cells are found in 7 or more nearby lymph nodes.

M categories indicate whether or not the cancer has spread (metastasized) to distant organs, such as the liver, lungs, or distant lymph nodes. M0: No distant spread is seen. M1a: The cancer has spread to 1 distant organ or set of distant lymph nodes. M1b: The cancer has spread to more than 1 distant organ or set of distant lymph nodes, or it has spread to distant parts of the peritoneum (the lining of the abdominal cavity).

Once a person's T, N, and M categories have been determined, usually after surgery, this information is combined in a process called stage grouping. The stage is expressed in Roman numerals from stage I (the least advanced) to stage IV (the most advanced). Some stages are subdivided with letters.

Another factor that can affect the outlook for survival is the grade of the cancer. Grade is a description of how closely the cancer resembles normal colorectal tissue when looked at under a microscope. The scale used for grading colorectal cancers goes from G1 (where the cancer looks much like normal colorectal tissue) to G4 (where the cancer looks very abnormal). The grades G2 and G3 fall somewhere in between. The grade is often simplified as either "low-grade" (G1 or G2) or "high-grade" (G3 or G4). Low-grade cancers tend to grow and spread more slowly than high-grade cancers. Most of the time, the outlook is better for low-grade cancers than it is for high-grade cancers of the same stage. Doctors sometimes use this distinction to help decide whether a patient should get additional (adjuvant) treatment with chemotherapy after surgery.

Colon cancer ranges from stages 0 to IV, with 0 being the least severe and IV being the most serious. In stage 0, the cancer is contained within the inner layer of the colon. In stage I, the cancer is grown through the inner layer, but hasn't spread beyond the colon. In stage II, the cancer has grown into or through the colon wall, and in stage III, the cancer has spread to the nearest lymph nodes. In stage IV, the cancer has spread far outside the colon to other organs.

Doctors describe colorectal cancer by stage, or extent of the disease. The wall of the colon and rectum is made up of several layers. If cancer forms in a polyp, it can eventually grow into the wall of the colon or rectum. When cancer cells are in the wall, they can grow into blood vessels or lymph vessels. Once cancer cells spread into blood or lymph vessels, they can travel to nearby lymph nodes or other parts of the body, such as the liver. The stage is based on whether the tumor has invaded nearby tissues, whether the cancer has spread, and if so, to what parts of the body.